1. Field of the Invention
This invention relates in general to a lightweight structural beam and, in particular, to a beam of folded corrugated cardboard for use in lightweight pallets.
2. Description of Related Art
Disposable corrugated cardboard pallets are known for use in areas where a lightweight pallet is required, for instance in transporting a number of boxes of foodstuffs such as boxes of cereal. Typically, the cardboard pallet is stored as a collection of flat cardboard sheets. Box beams are assembled by folding a flat sheet of cardboard which has been provided with a number of pre-scored folds, and gluing one or more flaps in place with an adhesive to prevent the box beam from disassembling. The pallet is subsequently constructed by sandwiching a number of assembled box beams between upper and lower platforms.
There have been a number of attempts at designing a box beam which is simple to assemble. A known example is disclosed in U.S. Pat. No. 4,563,377, which is directed to a corrugated cardboard beam composed of a single sheet of cardboard folded back on itself a number of times. The corrugated cardboard beam has two halves, one the mirror-image of the other, and each half composed of a diagonal section with the cardboard symmetrically folded back several times on itself on either side of the diagonal section. The corrugated cardboard beam is provided with suitable adhesive zones.
A difficulty with the corrugated cardboard beam of U.S. Pat. No. 4,563,377 is that it has a complex shape, requiring many folds to be made towards both sides of the cardboard sheet, thus making assembly of the cardboard beam difficult. In addition, the cardboard beam requires the use of adhesive to complete assembly. The need for glue introduces an extra step into the assembly process, increases assembly and material costs, and reduces the ability of the beam to be recycled.
There is therefore a need for a cardboard box beam which is simpler to assemble than existing box beams, but which retains the same high strength. A reduction in assembly complexity may be achieved by using fewer folds and also by ordering the folds so that the box beam requires fewer folds towards one of the surfaces of the cardboard sheet. In addition, there is also a need to avoid the requirement of providing adhesive during the assembly process, thus reducing cost and increasing recyclability.